${{\boldsymbol \psi}{(4390)}}$ $I^G(J^{PC})$ = $0^-(1^{- -})$

was ${{\mathit X}{(4390)}}$

This state shows properties different from a conventional ${{\mathit q}}{{\overline{\mathit q}}}$ state. A candidate for an exotic structure. See the review on non- ${{\mathit q}}{{\overline{\mathit q}}}$ states.